Life-history of Phalacrocera replicata. 315: 
except when the larva is feeding. The orifice of pro- 
trusion is a transverse cleft on the front of the prothorax. 
As usual in the retractile heads of Dipterous larvee, the 
hinder part, or occipital region, is imperfectly chitinised, 
and excavated by deep notches. No eyes or eye-spots 
have been found. There is a pair of small and slender 
antennz (figs. 8,9). The mandibles are small, but strong, 
curved inwards at the tip, and furnished, as is not un- 
common, with a fringe of sete, which help to close the 
mouth-opening (fig. 5). They are not externally visible, 
being enveloped within the maxille, which form the most. 
conspicuous appendages of the head (figs. 9, 10, 11). 
They appear on both dorsal and ventral surfaces, and 
consist of a number of sclerites, united by soft integu-. 
ment, and surmounted by small palps. The largest 
sclerites are ventral (fig. 11, sc.), and are furnished with 
brushes (b7.), which flank the labium on either side. In- 
ternal to these are subulate organs (so.), which possibly 
represent the labial palps. The so-called labium is a 
transverse plate, armed with teeth along its fore-edge, 
against which the mandibles act (figs. 10, 11, 12). As 
in some other Dipterous larvae, a second plate of similar 
outline overlies it (fig. 6). 
The body of the larva consists of eleven segments, 
most of which are subdivided into annuli. The varying 
number of the annuli, and the fact that in several seg- 
ments the dorsal and ventral annuli differ in number, 
show that their morphological value is slight. It may be 
added that they vary a good deal in different Dipterous 
larve. In the first three segments the annuli are ill- 
defined; there seem to be two dorsal and three ventral 
annuli in segments 2 and 8. Segment 4 has three dorsal 
(ill-defined) and four ventral ; segments 5 to 10 four 
dorsal and five ventral; and segment 11 no dorsal and 
perhaps three ventral. 
On the front surface of the prothorax is a large trans- 
verse Cleft, the orifice of invagination of the larval head. 
Above the cleft, when the head is protruded, a thick lip 
shows itself, which disappears from view when the head 
is completely retracted. ‘The lip is seen in sections to be 
a fold of the body-wall, which facilitates the protrusion 
and retraction of the head. Like the floor of the invagi- 
nation beneath the head, its morphologically external 
surface is covered with close-set setz. 
